The present invention relates to an integrated circuit device having a clock synchronization serial port function and timer function and including a microcomputer. More particularly, the invention relates to an integrated circuit device capable of achieving low power consumption.
As the conventional integrated circuit devices including microcomputers, there is one disclosed in JP-A-2001-325244. The invention disclosed in this publication relates to a semiconductor device having a timer function, as well as to a microcomputer and an electronic device. A semiconductor device 10 comprises a CPU 40, a timer controller circuit 30, a timer circuit 20, a port-output controller circuit 60 and the like. The timer circuit 20 performs a counting operation based on a timer value stored in a timer setting register 22. When a counter 24 overflows, the timer circuit generates a timer overflow signal, which is converted into a baud-rate clock by the port-output controller circuit 60 so as to be sent to a function block such as a clock synchronization serial port block or the like. The baud-rate clock is used as a master clock for a peripheral device in order that the semiconductor device may communicate with the peripheral device connected with the clock synchronization serial port block.
Unfortunately, the above conventional example involves a problem of high current consumption because the timer circuit must be constantly maintained operative for generating a baud-rate clock for the clock synchronization serial port block connected with a peripheral device communicating therewith at any frequency.